How to Live in a Japanese Apartment

Japanese Apartment Air Vents: How and Why to Use Them

In this series on “how to live in a Japanese apartment” we will explain some unique features found in Japanese apartments and how to use them in order to live comfortably in your home.

Air Vents (Kankikou)

Today’s chapter is on air vents (kankikou, 換気口), pictured in the lead photo. The air vents in your apartment may have a covering (pictured below) or may be located on the ceiling, and are usually installed in the living room and bedrooms.

Air vent in a Japanese apartment.

Should I always leave air vents open, even in the winter?

The common sense answer is, of course, to leave vents open to increase efficiency of air circulation in your home.

Air vents or ventilation openings were mandated by law as of July 2003 in the Japanese Building Standards Law as part of countermeasures against Sick Building Syndrome (SBS). As explained by the U.S. National Institute of Health, SBS is used to describe a situation in which the occupants of a building experience “acute health- or comfort-related effects that seem to be linked directly to the time spent in the building. However, no specific illness or cause can be identified.

When developers hand over a newly built condominium to owners, they also usually advise them to keep air vents open at all times, except in a typhoon.

Building inspectors also recommend that you always leave air vents open, even in the winter, or at least to leave your windows cracked.

What happens when you don’t ventilate: pressure build up and mold

Keeping your apartment tightly closed can have some unpleasant and downright unhealthy effects:

  • If you leave your windows tightly shut and don’t open air vents, it can make it difficult to open your front door and cause a loud bang and vibration as you try to pull it open. This is because Japanese apartments doors are usually made of steel to prevent the spread of fires. If you leave all your doors and windows closed and run your kitchen fan when you are cooking or the ventilator fan after you bathe, it will cause your apartment to build up a large amount of air pressure. The result is that you may have to pull hard on your front door in order to get inside. It will also cause your windows and sliding doors to shake.
  • Mold can be a serious problem due to Japan’s moist winters. If you don’t properly ventilate your apartment, it will create an ideal situation for mold to grow because it makes it much easier for condensation to form on your windows and walls.
Mold growing on an apartment sliding door.
Severe mold infestation in an apartment. In the winter, it is advised that you wipe down windows and walls periodically to prevent moisture. It’s also important to keep rooms well ventilated.

Wipe down vents and clean the filters

Is is recommended that you regularly wipe down your air vents and replace the filters to keep them working properly. You can buy them at home goods stores. They are called kankikou firutaa (換気口フィルター).

Dirty air vent filter. Photo: Yuko Tsuji, Home Inspector
Clean air vent filter. Photo: Yuko Tsuji, Home Inspector

You may also be interested in: How to Stay Warm at Home in Japan

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